NOVE.MIIEK lO. I 898 J 



NA TURE 



43 



liquiii. The amount of ozone in the gas was determined by 

 means of potassium iodide and sodium thiosulphate. The 

 resuhs gave for ozone a density of i '456 as compared with I for 

 oxygen ; the theoretical number being, of course, I '5. The 

 agreement, considering the difficulty of the experiments, is quite 

 satisfactory. In the course of the observations Prof. Ladenburg 

 found that water at ordinary temperatures and pressures does 

 not dissolve more than one-hundredth of its volume of ozone. 

 In attempting to determine the boiling point of liquid ozone it 

 appeared that this point lay at -I25°C. , but as soon as the 

 boiling commenced the liquid exploded with great violence and 

 reduced the whole apparatus to powder. 



The additions to the Zoological Society's Gardens during the 

 past week include a Serval {Felis sei-va/) from Africa, a Black- 

 footed Penguin {Spiienisciis dentersus) from South Africa, pre- 

 sented by Mr. H. S. H. Cavendish ; two Black-backed Jackals 

 {Cniiii misomelas) from South Africa, presented by Lady De 

 TratTiird ; a South Albemarle Tortoise (Testudo vui'iia) horn 

 South .\lbeniarle Island, Galapagos Group, presented by 

 Captain E. S. Tindall ; a Ring-tailed Lemur {Lemur cat/a) 

 from Madagascar, a Garnett's Galago [Gaiago gaine/li) from 



East -Africa, a Kangaroo (Donopsis, sp. inc.) from New 



Guinea, an Orange-winged Amazon {Chrysotis amazomca) from 

 South .-Xmerica, deposited ; two Spur-winged Geese {Plalro- 



pleiiis gambensis), two Fruit Pigeons {Phalacrotrcyoit 



ahyssini(a) from West Africa, two Bar-tailed Godwits [Limosa 

 lapponiiix), European, purchased ; a Bennett's Wallaby {,1/«- 

 cropus Ikiinel/i), two Squirrel-like Phalangers (Pclauriis sd- 

 un-tis), born in the Gardens ; six Glossy Ibises (Plegadis 

 faUinellus), bred in the Gardens. 



OUR ASTRONOMICAL COLUMN. 



The Leonids. — During the present week, if we are favoured 

 with line weather, the Leonid swarm or swarms of meteorites 

 should be very conspicuous, assuming they have not decreased 

 very considerably in number since the year 1865. That a great 

 number of observers will be on the watch for them, there is little 

 doubt, and photography will most probably be extensively used 

 for obtaining records in addition to the naked eye It may be 

 well here to sum up some of the important features which must 

 be noted when observing these moving strangers, and we cannot 

 do better than enumerate those given by Mr. Denning in his in- 

 teresting article (Observatory, 1S97) on this great meteor swarm. 

 Thu^', the observer should record the exact time of maximum 

 abundance, the number of meteors per minute, the position of 

 the centre of radiation, the area of this radiant if diffuse, and the 

 duration of the shower's chief activity. Further, their relative 

 magnitudes, duration of their visible flights, colou rs, and the 

 apparent paths of the brighter meteors should be noted. Many 

 othur peculiarities which the observer may remark, such as shape 

 of nuclei and apparent diameters of bolides (if there be any), 

 description of curved paths, broken streaks, and duration of 

 streaks with direction of their drift, should be faccurately re- 

 corded. .\ convenient form of table for entering such data could 

 be made with the following headlines : — Date, Greenwich Mean 

 Time, Magnitude, Observed path (from R.A., Dec. to R.A., 

 Dec), Length of trail, and Notes. 



It will be of in'erest to inquire whether the shower is divided 

 into three parts, as .Mr. Marsh has suggested. The following is 

 the preilicted times for these groups when they will be centrally 

 passed by the earth : — 



Precedina. Central. 



Nov. 14 



FolloNving. 

 ii 



Nov 



14 15 



21 5 



1S07 ... Nov. 13 9-25 



1^"^ - ,. 1575 .. 6-5 



i^oo „ 22-25 „ 13 



.\s there will be practically no moon to interfere with the 

 observations this year, every opportunity ought to be taken to 

 obtain a good record. Next year at the same period the moon 

 will be nearly full and visible the whole night, and this will un- 

 doubtedly interfere with observations, in spite of the fact that the 

 number of meteors reaches its maximum. 



The accompanying chart, which is a reproduction of that pub- 

 lished byiProf. W. H, Pickering in his account of the last year's 

 observations at Harvard, shows the position of the radiant point 

 in Leo and the neighbouring constellations. 



Further information concerning the probable appearance o, 

 this swarm of meteors will be found in the interesting article 

 contributed by our well-known authority on this subject, Mr. 

 Denning, in the present issue. 



Comet Brooks. — This comet is rapidly decreasing its declin- 

 ation and becoming fainter. The following ephemeris is based 

 on the elements of Ristenpart and MuUer. 



1898. R.\. (.npp.) Decl. (.ipp.) Br. 



Nov. II 



15 18 



7 39 6 

 4 50 '4 

 2 i6-3 



06 



0-5 



17 53 I 



17 57 14 



o 56 



The comet is still in the constellation of Ophiuchus, and on 

 the 15th will lie in the prolongation of a line joining k and j8 

 Ophiuchi at a distance from /3 of about one-third of that 

 between these stars. 



SiAKs WITH Great Velocities in the Line of Sight. — 

 Prof. W. W. Campbell, who is making spectrographic deter- 

 minations of stellar motions, has found evidences of large 

 velocities in .several of the stars he has examined, ■q Cephei is 

 one of the stars he mentions [Astrophysical foiiriia/, vol. viii. 

 No. 3), and the mean velocity deduced on five different 

 occasions from a discussion of 136 lines in the spectra amounts 

 to - 86 '8 kilometres per second ; this when corrected for solar 

 motion reduces to - 74T kilometres per second. The results 

 of Belopolsky for the brighter component of Q Herculis (Aslr. 

 A'lrc/;.'. , vol. 1 33, p 257-262)Jiave al.so been corroborated, the 

 corrected velocity amounting to - 53'9 kilometres per second. 

 It may be remembered that Prof. Keeler found for the planetary 

 nebula G.C. 4373 as a result from six nights of measurement, a 

 velocity of - 64 7 kilometres per second. 



>) Pegasi seems to have a very variable velocity, the extreme 

 range observed amounting to 23 kilometres per second. The 

 velocities that Prof Campbell has obtained up to the present 

 time are : — 



km. km. 



1596 Aug. 27 

 Sept. 23 



1597 July 8 

 Sept, 28 



We are evidently here dealing with a period somewliere about 

 two years in length. Prof. Campbell hopes that if other 

 observers have secured measureinents of this star, they will com- 

 municate their results to assist him in determining the period. 



NO. I 5 15, VOL. 59] 



